In recent years, not only personal computers, but also an increasing number of household appliances have a network connection function. However, programs that operate maliciously, such as spyware, may be released on networks. The danger of downloading and executing one of these programs is increasing. As a security measure under such conditions, research and development is underway into virtual machine system technology that executes a plurality of operating systems (virtual machines) simultaneously by generating an operating system (OS) as an environment for downloading and executing a non-trusted program in isolation from a safe OS.
In general, when executing a plurality of virtual machines simultaneously, the amount of memory necessary for execution increases, thus raising the manufacturing cost of the device. In order to reduce costs, methods of duplicating a virtual machine have been proposed (for example, see Patent Literature 1 and Patent Literature 2).